\documentclass[landscape]{sciposter}
\setmargins[0cm]
\usepackage{fontspec}
\usepackage{polyglossia}
\setdefaultlanguage{french}

\usepackage{graphicx}
\usepackage{tikz}
\usepackage[export]{adjustbox}

\defaultfontfeatures{Ligatures=TeX}
\setsansfont{EB Garamond}


\begin{document}

\begin{tikzpicture}[remember picture, overlay]
%-0.26,0.65)
      \node[anchor=north west] at (-0.26,-0.4){%
        \includegraphics{../maps/sheet52_indexedcolors_en.png}};
\end{tikzpicture}

\begin{tikzpicture}[remember picture, overlay]
      \node[align=center, text centered] at (0.5*\paperwidth, -1 )  {%
\huge \textbf{\textit{Carte générale \textsc{\&} particulière de la France}}, \textsc{n}{\Large o}. 52 \Large \textit{Clermont en Auvergne}: 1759-1777, 2016-2019};
\end{tikzpicture}


\begin{tikzpicture}[remember picture, overlay]
	  %\node[draw, ultra thin]       
      \node at (58,-77.7){%
        \includegraphics[scale=1]{images/maplegend/legend_en.png}};
\end{tikzpicture}

\begin{tikzpicture}[overlay]
      \node[anchor=north west] at (96 ,-74.7){%
        \includegraphics[height=3.5cm]{images/north_arrow.png}};
\end{tikzpicture}


\end{document}
